As the public safety market continues to require increased functionality of two-way radio, the association of public safety communications officials (APCO) through project 25 (P25) encourages participation of equipment suppliers and organizations to find solutions that meet the needs of the public safety market. In general, the APCO P25 standard specifies two approaches for providing application or centralized key management services to a subscriber unit (SU). The first approach employs common air interface (CAI) over the air rekeying (OTAR), and the second approach employs data link independent (DLI) OTAR which is also known as transport independent (TI) OTAR.
In the existing conventional systems, the subscriber units employing the CAI OTAR protocol can communicate and obtain key management application services only with an infrastructure system operating over or employing the CAI OTAR protocol. Similarly, the subscriber units employing the TI/DLI OTAR protocol can communicate and obtain key management application services only with an infrastructure system operating over or employing the TI/DLI OTAR protocol. However, migrating or moving the subscriber units employing the CAI OTAR protocol to the system or infrastructure having the DLI OTAR protocol currently requires replacement of the system's infrastructure and possibly its subscriber units. This is costly and undesirable.
In the existing technology, the challenge is that the CAI OTAR and TI/DLI OTAR based subscriber units cannot operate on the same channel or system. Other systems may face similar challenges when attempting to handle multiple protocols on the same channel or system.
Accordingly, there exists a need for providing application or OTAR services between two different standard protocols.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.